The Simian Immunodeficiency Virus (SlV)-infected Indian-origin rhesus monkey (Macaca mulatta) is the premiere animal model of human AIDS and has led to important advances in our understanding of disease pathogenesis, the role of viral determinants on disease progression, the impact of host immunity in controlling viral replication, and vaccine development. Rhesus macaques free of infection with Macacine herpesvirus 1 (B virus). Simian T lymphotropic Virus (STLV-1), Simian Retrovirus Type D (SRV-D), and SIV are essential to eliminate confounding variables associated with viral co-infections, to reduce the occupational health risks of working with macaques, and for overall colony health. The New England Primate Research Center (NEPRC) first established its specific-pathogen free (SPF) rhesus breeding colony in 1988, and the NEPRC SPF rhesus breeding colony is notable for its long history of i) high reproductive efficiency, ii) freedom from breaks in SPF status, iii) providing animals for AIDS-related investigations, and iv) cost-recovery. The goal of this application is to enhance the NEPRC SPF breeding colony production of well-characterized, SPF offspring for AIDS-related studies by optimizing colony management for maximum space utilization, maintaining high level reproductive efficiency, and improving behavioral management and environmental enrichment. Recently, with ARRA support, we have also MHC typed our entire SPF breeding colony using 454 sequencing providing important and unprecedented characterization for the MHC diversity of the breeding colony. The specific aims of this application are as follows: Specific Aim #1: Enhance and sustain the NEPRC rhesus macaque SPF breeding colony. Specific Aim #2: Continue MHC typing and genetic testing to provide for informed colony management and well-characterized animals for AIDS-related investigations.